This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-303281 filed on Oct. 3, 2000.
1. Field of the Invention
The present invention relates to an automatic optical-axis adjusting device for automatically adjusting directions of optical axes and illuminating zones of front lights of a vehicle with respect to a steering angle of a steering wheel.
2. Description of Related Art
One automatic optical-axis adjusting device for automatically adjusting optical axes of front lights of a vehicle is disclosed, for example, in Japanese Patent No. 2950897. Japanese Patent No. 2950897 discloses a technique for changing the optical axes of the front lights (vehicle lamps) based on a steering angle of a steering wheel of the vehicle. More specifically, a non-sensing region is provided around a neutral point of the steering angle of the steering wheel. Movements of the optical axes of the front lights are prevented when the steering wheel is steered within the non-sensing region. In this way, the optical axes of the front lights are not varied when the steering wheel is steered within a play angle of the steering wheel around the neutral point of the steering wheel. A width of the non-sensing region varies in response to a vehicle speed. More specifically, the width of the non-sensing region increases as the vehicle speed increases, so that the swivel control operation of the front lights is carried out in a manner that is inconsistent with a driver""s demand.
However, in this automatic optical-axis adjusting device, the optical axes of the front lights are adjusted in the left or right direction in a sensitive manner with respect to the small steering movements of the steering wheel at an outside of the non-sensing region of the steering wheel, causing an uncomfortable feeling to the driver.
The present invention addresses the above disadvantage, and it is an objective of the present invention to provide an automatic optical-axis adjusting device for automatically adjusting a direction of an optical axis of each corresponding front light of a vehicle based on a steering angle of a steering wheel without causing an uncomfortable feeling to a vehicle driver.
To achieve the objective of the present invention, there is provided an automatic optical-axis adjusting device for automatically adjusting a direction of an optical axis of at least one front light of a vehicle. The automatic optical-axis adjusting device includes a steering angle measuring means, a response changing means and a swivel control means. The steering angle measuring means is provided for measuring a steering angle of a steering wheel of the vehicle. The response changing means is provided for changing a response in swivel adjustment of the direction of the optical axis of the at least one front light of the vehicle based on an angular positional change rate of the steering angle measured with the steering angle measuring means. The swivel control means is provided for adjusting the direction of the optical axis of the at least one front light with respect to the steering angle measured with the steering angle measuring means based on a control angle obtained through the response changing means.